TiN electrode-induced bipolar resistive switching of TiO2 thin films

The bipolar resistive switching characteristics in polycrystalline TiO2 thin films after regular forming process were studied using two different top or bottom TiN electrodes (Sample A: top TiN/TiO2/Pt, Sample B: Pt/TiO2/TiN bottom). The sample A and B clearly showed two different switching directions of counter-clockwise (CCW) and clockwise (CW) bipolar switching behaviors, respectively, depending on the relative position of the TiN electrode. These switching characteristics in both samples could be understood by considering the forming and rupture of the conducting path due to the migration of oxygen ions between the TiO2 layer and the TiN electrode, which acts like the oxygen reservoir. In addition, both samples clearly display high reliable memory switching characteristics, such as stable switching speed (μs), endurance behaviors (>104), and long retention times (>104 s).